Cut-out model of an Orthocone nautiloid

Orthocone nautiloids were extinct ancestors of the tightly coiled Pearly Nautilus that is still found swimming in the deep oceans. Orthocones were distant relatives of extinct ammonites and modern squid and octopus. Orthocones lived from about 500 million years ago until nearly 200 million years ago. The soft body and tentacles are rarely preserved as fossils but the hard shells are often fossilised in large numbers.